A: The rectangular iron sheet is 6.28 decimeters long and 3 decimeters wide.
2. two kinds. One uses a 5 cm edge as the bottom of the cylinder, and the height at this time is 4 cm.
One has a side of 4 cm as the bottom of the cylinder, and the height is 5 cm at this time.
3. The circumference of the bottom surface of the seeder drum: 2x3.14x (1/2) = 3.14 (m).
Cylinder area of seeder drum: 3.14x1= 3.14 (square meter)
The seeder can roll 100 * * for sowing: 3.14x100 = 314 (square meter).
4, saw three sections, one * * * has six more bottoms. Surface area increase: 3.14x (square of 20) X6=7536 (square centimeter)
5, 1 liter = 1 cubic decimeter
The height of water in the bucket is: (40/6)X(3/4)=5 (decimeter).
Application questions:
1, and the radius of water pipe is: 6/2=3 (cm) = 0.03m for half an hour = 1800s.
Discharge per second: 3. 14X(0.03 square) X4
Half-hour effluent: 3.14x (0.03m2) X4X 1800=20.3472 (m3).
2. The circumference of the front wheel is 2X3. 14X(2/2)=6.28 (m).
The area of front wheel cylinder is 6.28X 1.5=9.42 (m2).
The number of meters in half an hour is: 6.28X 15X30=2826 (meters).
The road area covered after one hour's work is 9.42X 15X60=8478 (square meter).
3. The diameter and height of the bottom of the cylinder are: root number 36=6 (cm) and radius 3 cm.
The circumference of the cylinder bottom is 2X3. 14X3= 18.84 (cm).
The bottom area of the cylinder is: 3.14x (the square of 3) =28.26 (square centimeter).
The area of the column is:18.84x6 =113.04 (square centimeter).
The surface area of the cylinder is 28.26x2+113.04 =169.56 (square centimeter).